Field of the Invention
This invention relates generally to blood lancet which is used to prick a skin site for obtaining small volume of capillary whole blood for subsequent blood testing.
Background of the Invention
Skin penetration is insertion of at least a pointed article into the skin with depths ranging from tens of microns to less than three millimeters. Depending on the purpose, there are several methods and devices currently available for skin penetration. For transdermal drug delivery purpose, small cluster of needles (microneedles) are inserted into the skin to puncture the outer layer of skin which is otherwise a barrier for drug delivery into the skin. The term ‘drugs’ is, a general referred to medicinal substance such as hormones, drugs, vaccines etc. Such microneedles are sometimes inserted into the skin by bare hand or a hand held device to extract bodily fluids such as plasma etc. for analysis. Most of these devices and methods are still in clinical trial phase and are not available on the market. These devices are normally made in sophisticated processes. In addition, they require extra packaging effort in keeping them sterile till point of use and extra care for disposal to prevent accidental injuries or re-use.
For blood sampling purpose, the pointed article (better known as blood lancets, normally with needle length of 3 mm) is used with a spring-operated applicator which inserts the blood lancet into the skin and retracts it at a very high speed. Since the speed is very high (often more than 1,000 mm/sec), the duration of the blood lancet staying in the skin is very brief (often a few milliseconds), so the discomfort or pain incurred is minimal. The applicator's distal end which contacts the skin has an opening for the lancet to penetrate the skin. The opening also serves an important role in fixing the skin such that certain rigidity and surface tension are reached for optimal skin penetration. Without the fixation of the skin, the skin penetration result will be inconsistent and much more painful.
The current blood lancets are made by over-moulding a stainless steel needle with inexpensive polymer such as polyethylene or polypropylene to form a handle. A cap, which can be moulded separately or integrally moulded, is put on the tip to conserve the sterile conditions till point of use. Due to the slenderness of the stainless steel needle, there is no anchoring or fastening of it to the plastic body, making it vulnerable to slip out of the body. Slippage of the stainless steel needle will make the effective length longer than designed and will cause extra pain or injuries. There is also no prevention for accidental injuries and re-use after the blood lancets are disposed of, except that users are advised to dispose the used lancets in a sharps collector. The stainless steel needles remain sharp which may pose a great potential threat to the personnel handling the disposal. There is also a possibility that the used needles are collected for re-use.
Moreover, the current stainless steel lancet with plastic body have many manufacturing steps and different machines, such as handling and making the stainless steel needle, before moulding a plastic body and cap to encase the stainless steel needle. This inevitably drives up the cost of the blood lancets. In addition, the device comprising stainless steel and polymer is difficult to recycle as the stainless steel (1200 degree Celsius) has much higher melting temperature to polymers (<350 degree Celsius). In addition, the stainless steel needle imposes an injury threat to the medical personnel who handle the disposal of the lancets. The cap is not an adequate measure in preventing accidental injuries or re-use because it may not be capped after use or may be removed accidentally or intentionally.